NASA`s new telescope can detect signs of life on planets orbiting white dwarfs

Washington: The James Webb Space Telescope (JWST), set to be launched by NASA in 2018, will be capable of detecting oxygen and water in the atmosphere of an Earth-like planet orbiting a white dwarf after only a few hours of observation time-much more easily than for an Earth-like planet orbiting a Sun-like star, say researchers.

Because it has no source of energy, a white dwarf will eventually cool down and fade away. But circumstantial evidence suggests that white dwarfs can still support habitable planets, said Prof. Dan Maoz of Tel Aviv University`s School of Physics and Astronomy.

Now Prof. Maoz and Prof. Avi Loeb, Director of Harvard University`s Institute for Theory and Computation and a Sackler Professor by Special Appointment at TAU, have shown that, using JWST, it should be possible to detect biomarkers surrounding these planets-including oxygen and methane-that indicate the presence of life.

"In the quest for extraterrestrial biological signatures, the first stars we study should be white dwarfs," said Prof. Loeb.

Prof. Maoz agrees, noting that if "all the conditions are right, we`ll be able to detect signs of life" on planets orbiting white dwarf stars using the much-anticipated JWST.

An abundance of heavy elements already observed on the surface of white dwarfs suggest rocky planets orbit a significant fraction of them. The researchers estimate that a survey of 500 of the closest white dwarfs could spot one or more habitable planets.

The unique characteristics of white dwarfs could make these planets easier to spot than planets orbiting normal stars, the researchers have shown.

Their atmospheres can be detected and analyzed when a star dims as an orbiting planet crosses in front of it. As the background starlight shines through the planet`s atmosphere, elements in the atmosphere will absorb some of the starlight, leaving chemical clues of their presence-clues that can then be detected from the JWST.

In order to estimate the kind of data that the JWST will be able to see, the researchers created a "synthetic spectrum," which replicates that of an inhabited planet similar to Earth orbiting a white dwarf. They demonstrated that the telescope should be able to pick up signs of oxygen and water, if they exist on the planet.

The JWST will be ideal for hunting out signs of life on extraterrestrial planets because it is designed to look into the infrared region of the light spectrum, where such biomarkers are prominent. In addition, as a space-based telescope, it will be able to analyze the atmospheres of Earth-like planets outside our solar system without weeding out the similar signatures of Earth`s own atmosphere.

The researchers published their work in the Monthly Notices of the Royal Astronomical Society.